Apparatus for dispensing adhesive



Feb. 11, 1969 c, HARRMAN 3,426,945 1 APPARATUS FOR DISPENSING ADHESIVESheet F1196. June 26 1967 INVENTOR; A//en C. Harri/nan 4%;

EM I 1477"? Feb. 11, 1969 A. c. HARRIMAN APPARATUS FOR DISPENSINGADHESIVE w Q y no N a 2 0 W r t 4. m m ,Q S m \\\s M 4 I 2D m 1 HI 6 n wW w, N/m 3. M IlI 4 ILW 9 J I? a 1, 4 w \Z w 6% Q my, w HQ MIJI+IY r mW, H s a mm ,1: a p x4, a u M w y V W a 7 m M 4 "M a, a f e K x a Z w1.1M! W k m. M D i\i 1|.) F m H k z 4/ F m m Q M m m M a 1.1 K

Feb. 11, 1969 A, c. HARRIMAN APPARATUS FOR DISPENSING ADHESIVE FiledJuhe 26, 1967 an 1k E. MM 0 new m FIG-9 FIG-l0 United States PatentClaims ABSTRACT OF THE DISCLOSURE Disclosed herein is a fluid dispensersuitable for use with thermoplastic materials. The device includes amelting chamber in which fluid is stored. The chamber has a base inwhich a pumping unit is contained, the pumping unit being adapted topump fluid from the chamber to and out of a discharge orifice. Theconstruction of the pump unit is such that after it causes apredetermined volume of fluid to be dispensed from the discharge orificesome of the residual, undispensed fluid is withdrawn back towards thepump, away from the orifice, thus tending to minimize drip and leakagebetween dispensing cycles.

SUMMARY OF THE INVENTION The instant invention is directed to anapparatus 101. dispensing a fluid by pumping the fluid through andtowards the discharge orifice of a conduit so as to dispense fluidtherefrom. The pumping of fluid towards the orifice is then stopped andthe flow of fluid in the conduit is reversed so as to withdraw the fluidinto the conduit and away from the discharge orifice the effect of whichbeing that the tendency of fluid to drip or leak from the orificebetween pumping cycles is minimized.

The apparatus includes a conduit having a discharge orifice at one endthereof, first pumping means associated with said conduit for pumpingfluid through said conduit towards and out of said discharge orifice,and a valve disposed along said conduit between said first pump meansand said discharge orifice. The conduit is normally filled with fluid,the valve being open, and the first pump means is then operated to causefluid to be dispensed from the discharge orifice. The valve then isclosed to block the conduit and a second pumping means is then operatedto draw a portion of the fluid that remained in that portion of theconduit between the valve and orifice back through and out of theconduit so that when the unit is idle, fluid will not be at the tip ofthe orifice, thus minimizing drip and leakage therefrom. Means areprovided for returning the first pump mean-s to its idle position andfor refilling the first pump means while the valve is closed and thesecond pump means is operating.

Th subject of the instant invention may be used in conjunction with anyenvironment in which a fluid, such as molten thermoplastic adhesive, isto be dispensed. By way of example, it may be incorporated into anapparatus such as that disclosed in U.S. patent application Ser. No.610,097, filed Jan. 18, 1967, in pumping a measured charge of moltenthermoplastic adhesive through dispensing outlets disclosed therein ontoa shoe part.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

FIGURE 1 is a plan view of the illustrative embodiment of the instantinvention;

FIGURE 2 is a front elevation of the device;

FIGURE 3 is a sectional view of the device taken along the line 33 ofFIGURE 1;

FIGURE 4 is a sectional view taken along the line 44 of FIGURE 1;

FIGURE 5 is a plan view in section of the pumping units taken along theline 5-5 of FIGURE 4 and illus 3,426,945 Patented Feb. 11, 1969 tratingthe position of the members of the pumping units prior to the beginningof the pumping cycle;

FIGURE 6 is a view similar to that of FIGURE 5 illustrating the pumpingunits with the valves having been rotated to a position wherein fluidmay be dispensed from the pumping units;

FIGURE 7 is a view similar to FIGURE 5 illustrating the positions of themembers of the pumping units after fluid has been discharged therefrom;

FIGURE 8 is a view similar to that of FIGURE 7 and illustrating theshifting of the valves so as to enable the pumping units to be refilledand to enable the fluid to be withdrawn from the discharge outlet;

FIGURE 9 is a substantially schematic view of the nozble with a portionthereof broken away to illustrate the withdrawal of fluid from thedischarge orifice;

FIGURE 10 is a view similar to that of FIGURE 9 illustrating thetendency for fluid to drip from the nozzle; and

FIGURE 11 is a schematic of the control system for operating the pumpingunit in the proper sequence.

Referring to FIGURES 1-4, the device includes a pot 10 having a loadingchamber 12 and a pump chamber 14. The chambers 12 and 14 are separatedby a relatively coarse screen 16 which is secured to upstanding walls 18that are formed at the interior of the pot 10. A top plate 20 is securedto and covers the pump chamber 14 of the pot 10. A cover 22 overlies theloading chamber 12 and is connected to the top plate 20 by means of ahinge 24 to provide access to the loading chamber 12. A knob 26 issecured to the cover plate 22. In loading the device, the cover 22 israised and the material to be dispensed, such as a thermoplasticmaterial, is loaded into the loading chamber 12. As may be seen fromFIGURES 3 and 4, heaters 28, 30 are provided about the pct 10 to meltthe material whereupon it may flow through the screen 16 and into thepumping chamber 14. The screen 16 serves to preclude entry of unmeltedlarge solid particles into the pumping chamber 14.

In the illustrative embodiment of the invention there are two distinctpumping units 32 and 34 (see FIGURES 4 and 5). For the purpose ofsimplicity of explanation, only the pumping unit 32 will be described indetail, the operation of the other pumping unit 34 being described onlyto illustrate the differences therebetween. Referring to FIG- UrR'E 3, aplug 36 is disposed within the pump chamber 14 and is secured to thebase 38 of the pct 10. A number of conduits 40 are formed within theplug 36 and serve to communicate the pump chamber 14 with the pumpingunit 32 that is disposed within the base 38. The pumping unit 32includes a primary conduit 42 having a first portion 43 and a secondportion 44. A rotary valve 46 serves to connect the first and secondportions 43 and 44 in a manner later described. A supply conduit 48which is in communication with the pump chamber 14 by means of the plug36 is also formed so .as to be in communication with the valve 46. Apair of bores 50 and 52 that intersect respectively, the first andsecond portions 43 and 44 of the primary conduit 42 are formed withinthe base 38 of the pot 10. Associated with each of the bores 50 and 52are the plungers 54 and 56. Each of the plungers 54 and 56 is secured toa piston 58 that is slidable within a counterbore 60, such that movementof each of the pistons 58 along its counter-bore '60 will effectmovement of the plungers 54 and 56 axially within their respective bores50 and 52. Movement of the plungers 54, 56 towards the primary conduit42 will hereinafter be referred to as forward and movement of theplungers 54, 56 away from the primary conduit 42 will be referred to asrearward.

The rotay valve 46 of the pumping unit 32 is formed at the lower end ofa shaft 62 that is rotatable within a bore 64 formed within the base 38of the pot 10. The

bore 64 is in communication with and connects the portions 48 and 44.The valve 46 comprises a conduit 66 formed along the diameter of thelower part of the shaft 62 and a kenf 68 that is in communication withthe conduit 66. The valve 46 is caused to be rotated between twopositions, the first of which, illustrated in FIGURE 6, wherein the kerf68 and conduit 66 of the valve 46 are so aligned as to effectcommunication between the first and second portions 43, 44 of theconduit 42 with the supply conduit 48 being blocked, and a secondposition, illustrated in FIGURE 5, wherein the valve 46 has been rotated(clockwise, as seen in FIGURE to effect closure of the passage betweenthe first and second portions 43 and 44 and effect communication betweenthe supply conduit 48 and the second portion 44 of the conduit 42 bymeans of the kerf 68.

When the pump 32 is in idle position, as illustrated in FIGURE 6, thevalve 46 is rotated to its first position and the piston 58 and plungers54 and 56 are in a rearward position. The first and second portions 43,44 of the conduit 42 and bores 50 and 52 are filled with moltenthermoplastic material, as are the conduit 66 and kerf 68 of the valve46. The pistons 58 are then urged forwardly, !by means later described,to move the plungers 54 and 56 forwardly within their respective bores52 and 54 thus pumping the fluid material to the outlet 70 at the end ofthe first portion 43 of the conduit 42. The fluid that is in the firstbore 50 flows out of the first bore 50, into the first portion 43 of theconduit 42, and into a hose 69 that serves as an extension of and is incommunication with the first portion 43 of the conduit 42 by means ofthe fitting 70. At the end of the hose 69 is a dispensing nozzle 71having a discharge orifice 7 3 through which the fluid is dispensed (seeFIGS. 8, 9, By way of example a nozzle of the type disclosed in US.patent application Ser. No. 610,097, filed Jan. 18, 1967 may be used.The fluid in the second bore 52 flows out of the second bore 52 throughthe second portion 44 of the conduit 42, through the valve 46, into thefirst portion 43 where it joins the flow from the first bore 50. Afterthe fluid has so been pumped to the nozzle 71, plungers 54 and 56 andvalve 46 are in the configuration illustrated in FIG- URE 7.

After completion of the pumping operation, the valve 46 is caused to berotated to the configuration illustrated in FIGURE 8, from which it maybe seen that the kerf 68 serves to communicate the second portion 44 ofthe conduit 42 and the supply conduit 48, with communication between thefirst and second portions 43, 44 being blocked. With the valve 46 sorotated, the pistons 58 are caused to be moved rearwardly to their idlepositions, as shown in FIGURE 5, to retract the plungers 54 and 56within their respective bores 50 and 52. Retraction of the plunger 54 isretracted, a portion of the fluid material that is contained within thefirst portion 43 of the conduit 42, the hose 69 and nozzle 71, and thathad not been dispensed the second portion 44 of the conduit 42 and thebore 52, thus refilling this portion of the pump unit 32 in readinessfor operation of the succeeding cycle thereof. As the plunger 54 isretracted, a portion of the fluid material that is contained within thefirst portion 43 of the conduit 42, the hose 69 and nozzle 71, and thathad not been dispensed through the nozzle 71, is drawn back through thehose 69 and first portion 43 of the coduit 42 and into the bore 50. Thevolume of fluid material that is so withdrawn is equal to thedisplacement of the plunger 54 within the bore 50. The bore 50 thusserves as a storage unit for the withdrawn fluid. Thus, retraction ofthe plunger 54 will cause a predetermined volume of fluid material to bewithdrawn from the discharge orifice 73 of the nozzle 71. It should benoted that when the invention is used with fluids of a relatively highviscosity the tendency for the fluid to drip from the nozzle 71 will beless than if a fluid of lower viscosity is used. For this reason, whenusing the less viscous fluids the displacement of the plunger 54 shouldbe increased so that a greater volume of fluid will be withdrawn fromthe discharge orifice 73 of the nozzle 71. The effect of this is toinsure that even if there is a tendency for the fluid to flow out of thenozzle the length of time required for the fluid to flow from the pointto which it was withdrawn to the outlet of the nozzle will be greaterthan the time elapsed between operating cycles of the pumping unit 32 sothat before the fluid can actually drip from the nozzle the pumping unit32 is again operated to forcibly and intentionally dispense the fluid.FIGURE 10 is illustrative of fluid beginning to flow from its withdrawnposition to the discharge orifice 73 of the nozzle 71. The 'valve 46 maythen be rotated to the position shown in FIGURE 6 in readiness for a newcycle of operation.

Referring to FIGURES 1, 2 and 3 the drive means for effecting actuationof the plungers 54 and 56 includes an air-operated motor 72 that ispivotally secured at one end thereof to a bracket 74 which in turn issecured to the frame 76 on which the pot 10 is mounted. The motor 72 hasan upwardly extending piston rod 78 and a clevis 80 secured to andextending upwardly from the free end of the piston rod 78. The clevis 80is pinned to one end of a lever 82, the other end of the lever 82 beingsecured to a shaft 84 that is rotatably mounted in trunnions 86 thatextend upwardly from the top plate 20. Secured to the shaft 84 are apair of downwardly extending arms 88, the lower ends of which extendinto slots 90 formed in the pistons '58. The top plate 20 is providedwith slots 92 to enable the arms 88 to extend downwardly therethroughand slots 94 are formed in the base 38 and extend lengthwise of thebores 60 so as to enable the downwardly extending ends of the arms 88 toengage the pistons 58. It may thus be seen that actuation of the motor72 to lower the piston rod 78 may cause the shaft 84 to rotate(clockwise as seen in FIGURE 3) thus causing the lower ends of the arm88 to urge the pistons 58 forwardly, thereby effecting forward movementsof the plungers 54 and 56 in a pumping stroke. Conversely, upwardmovements of piston rod 78 will effect a swinging of the arm 88 in acounter-clockwise direction (as seen in FIGURE 3) to retract the pistons58 and plungers 54 and 56 rearwardly to their normally idle positions.The length of the stroke of the plungers 54, 56 may be varied by meansof a stop screw 96 that is adjustably rotatable within the lever 82 andis adapted to abut the head of a bolt 98 fastened to the cover plate 20.The screw 96 serves to limit the extent of movement of the lever 82 andconsequently the arm 88 which in turn governs the stroke anddisplacement of the plungers 54, 56.

The structure and operation of the pump unit 34 is substantiallyidentical to that of the pump unit 32. In the drawings those parts ofthe pump unit 34 that are substantially identical to and perform thesame function as corresponding parts of the pump unit 32 are denoted byidentical numerals followed by a prime mark For example, the pistons ofthe pump unit 32 designated as 58 are referred to in the pump unit 34 as58. The valve 100 of the pump unit 34 is of slightly differentconstruction than that of the pump unit 32. In the illustrativeembodiment of the invention this is necessitated as a result of theparticular drive mechanism utilized to effect rotation of the valves 46and 100. The mode of operation and function of the valves 46 and 100,however, is the same.

The rotation of the valves 46 and 100 is effected by means of anair-actuated motor 102 that is pivotally connected to the bracket 74 andhas an upwardly extending piston rod 104 the end of which is pivotallyconnected to one end of a bell crank lever 106. The *bell crank lever106 is pivotally mounted on a bracket 108 that is secured to the topplate 20 (see FIGURES l, 2, and 3). The other end of the bell cranklever 106 is pivotally connected to the end of a forwardly extending rod110. The other end of the rod 110 is pivotally connected at the pivotpin 112 to the ends of actuating levers 114 and 114'. The actuat inglever 114 is secured to the upper end of the cylinder 62 and theactuating lever 114 is secured to the upper end of the cylinder 62 whichis journaled for rotary movement in the top plate by means of bearings116. It may thus be seen that when the piston rod 104 of the motor 102is urged upwardly the shafts 62 and 62 Will be rotated to a positionwherein the valves 46 and 100 that are formed integrally with the bottomportions of the cylinders 62, 62' are in to their first position asillustrated in FIGURE 6. Conversely, when the piston rod 104 of themotor 102 is urged downwardly the valves 46 and 100 will be rotated totheir aforesaid second position illustrated in FIGURE 5. It should benoted that the cylinders 62 and 62' and consequently the valves formedtherein rotate in opposite directions; that is, when the valves 46 and100 rotate from their first position to their second position the valve46 rotates clockwise, whereas the valve 100 rotates counter-clockwise asseen in FIGURE 5. Conversely, when the valves are rotated from theirsecond to their first positions the valve 46 rotates counter-clockwiseand the valve 100 rotates clockwise.

The difference in directions of rotations of the valves 46 and 100necessitates a different configuration in the passageways of the valves46 and 100*. Thus the kerf 118 of the valve 100 although serving thesame purpose as that of the kerf 68 of the valve 46 does not intersectthe passageway 120 formed in the valve 100.

Referring again to the pumping unit 32, when it is in an idle positionand in readiness to pump fluid material therefrom the fluid materialcontained within the first portion 43 of the conduit 42 does not extendto the tip of the outlet 70, the volume which is unoccupied by the fluidbeing equal to the volume of fluid that had been withdrawn during theprevious cycle of operation by means of rearward movement of the plunger54 within the bore 50. Thus in order to dispense a predetermined volumeof fluid from the nozzle 71 the volume of fluid that is pumped throughthe first portion 43 of the conduit 42 must be equal to that volumewhich is desired to be discharged plus the volume which had beenpreviously withdrawn. The plunger 54 and bore 50 supply the volume offluid necessary to completely fill the first portion 43 of the conduit42 and the plunger 56 has a displacement equal to the volume of thefluid that is to be discharged from the orifice 73. Thus thedisplacement of the plunger 54 governs the extent of withdrawal of fluidwithin the first portion 43 of the conduit 42 and the displacement ofthe plunger 56 governs the volume of fluid that is actually dispensedfrom the orifice 73 of the nozzle 71.

Actuation of the motors 72 and 102 to operate respectively the plungers54, 56 and the rotary valve 46 in the aforementioned sequence iseffected by a pneumatic circuit ilustrated schematically in FIGURE 11. Asource of compressed air S is connected by means of the line 122 to theinlet of a valve 124. The outlet of the valve 124 is connected by meansof the line 126 and the line 128 to the rod end of the motor 72. Thehead end of the motor 102 is also connected to the outlet of the valve124 by means of the line 126 and line 130. A restriction 132 is providedin the line 128 for restricting the flow of air therethrough to themotor 72. It may thus be seen that when the valve 124 is shifted fromits normally closed position to a position wherein compressed air mayflow from the source S thereof through the line 122, the valve 124, theline 126 and then into both of the lines 128 and 130 to urge the pistonrod 78 of the motor '72 downwardly thereby urging the plungers 54, 56'forwardly in a pumping stroke and urging the piston rod 104 of the motor102' upwardly to cause the valve 46- to shift to its second positionwherein the aforementioned pumping stroke is permitted. The restrictorvalve 132 located in the line 128 insures that the motor 102 will beactuated before actuation of the motor 72 so that the valve 46 will havebeen rotated to its second position before initiation of the pumpingstroke. After the pumping stroke has been completed and the fluid hasbeen dispensed from the discharge orifice 73 of the nozzle 71 the motors72 and 102 are reversed to rotate the valve 46 to its first positionthus enabling the withdrawal of fluid from the discharge orifice 73 ofthe nozzle 71 and the refilling of the pump unit 32 for a succeedingcycle of operation. The reversal of the motors 72 and 102 is effected bymeans of flow of compressed air from the source S through the line 134,the valve 136, the line 138 and into the line 140 which is connected tothe head end of the motor 72 and into the line 142 which isconnected tothe rod end of the motor 102. The valve 136 which is normally closed isactuated by a cam. or other suitable means to enable the compressed airto follow the aforementioned path into the lines 140 and 142 to causethe piston rod 104 of the motor 102 to be retracted downwardly therebyrotating the valve 46 to its first position and causing the piston rod78 of the motor 72 to be urged upwardly thereby drawing the plungers 54,56 rearwardly. A restrictor valve 144 is located in the line 140 toinsure that the motor 72 is not actuated until after the motor 102 hasbeen actuated and the valve 46 has been rotated to its first position.Each of the valves 124 and 136 are of such construction that air that isexhausted from either end of either motor may flow through the linesassociated therewith and to its associated valve and be exhausted to theatmosphere.

The foregoing disclosure is to be understood as defining only anillustrative embodiment of the invention, the scope of which is definedin the appended claims.

-I claim:

1. A fluid dispensing system comprising: a source of fluid; a primaryconduit having a discharge orifice, a first portion and a secondportion, the first portion being between the discharge orifice and thesecond portion; a first fluid storage unit in communication with saidfirst portion; a second storage unit in communication with said secondportion; a movable valve in the primary conduit, located between saidfirst and second portions, so constructed as to permit communicationbetween said portions when in a first position and to blockcommunication between said portions when in a second position; meansproviding communication between the source and the second storage unitwhen the valve is in said second position; means for initiallymaintaining the valve in said first position with the primary conduitand the storage units filled with fluid; means for thereafter forcingthe fluid from both storage units into the primary conduit to therebydispense fluid from the discharge orifice; means for thereafter movingthe valve from its first position to its second position; and means forthereafter drawing fluid from the primary conduit into the first storageunit and for drawing fluid from the source into the second storage unit.

2. The system as defined in claim 1 wherein said first storage unitcomprises: a first bore in communication with said first portion; and afirst plunger mounted in the first bore for movement between a rearwardposition remote from said first portion and a forward position that iscloser to said first portion; wherein said second storage unitcomprises: a second bore in communication with said second portion; anda second plunger mounted in the second bore for movement between arearward position that is remote from said second portion and a forwardposition that is closer to said second portion; wherein both plungersare initially maintained in their rearward positions; wherein said meansfor forcing the fluid from both storage units into the primary conduitcomprises means for moving both plungers from their rearward to theirforward positions; wherein the means for drawing fluid from the primaryconduit into the first storage unit comprises means for moving the firstplunger from its forward position to its rearward position; and whereinthe means for drawing fluid from the source into the second storage unitcomprises means for moving the second plunger from its forward positionto its rearward position.

3. The system as defined in claim 1 further comprising:

a supply conduit connecting the source and the valve; and wherein saidvalve is so constructed as to permit communication between the supplyand the second storage unit when the valve is in said second position tothereby constitute said means providing communication between the sourceand the second storage unit.

4. The system as defined in claim 1 further comprising:

a supply conduit connecting the source and the valve; wherein said firststorage unit comprises: a first bore in communication with said firstportion; and a first plunger mounted in the first bore for movementbetween a rearward position remote from said first portion and a forwardposition that is closer to said first portion; wherein said secondstorage unit comprises: a second bore in communication with said secondportion; and a second plunger mounted in the second bore for movementbetween a rearward position that is remote from said second portion anda. forward position that is closer to said second portion; wherein saidvalve is to constructed as to permit communication between the supplyand the second bore when the valve is in said second position to therebyconstitute said means providing communication between the source and thesecond storage unit; wherein both plungers are initially maintained intheir rearward positions; wherein said means for forcing the fluid fromboth storage units into the primary conduit comprises means for movingboth plungers from their rearward to their forward positions; whereinthe means for drawing fluid from the primary conduit into the firststorage unit comprises means for moving the first plunger from itsforward position to its rearward position; and wherein the means fordrawing fluid from the source into the second storage unit comprisesmeans for moving the second plunger from its forward position to itsrearward position.

5. A fluid dispensing system comprising:

a base member;

a primary conduit formed within said base member and having a dischargeorifice formed at one end thereof;

a. supply conduit formed within said base member, said supply conduithaving one end thereof in communication with said primary conduit at acommon juncture intermediate the ends of said primary conduit and theother end thereof adapted to be in communication with a source of fluid;

a first bore formed within said base member and being in communicationwith the other end of said primary conduit;

a first plunger slidably contained for reciprocating movement withinsaid first bore so as to be capable of pumping fluid into and out ofsaid other end of said primary conduit;

valve means disposed at said common juncture and being operable betweena first position wherein communication is established between said otherend of said primary conduit and said discharge orifice whilecommunication between said supply conduit and said common juncture isblocked and a second position wherein communication between said otherend of said primary conduit and said discharge orifice is blocked andcommunication between said supply conduit and said other end of saidprimary conduit is established;

a second bore formed within said base member and being in communicationwith said primary conduit at a point intermediate said discharge orificeand said common juncture;

a second plunger slidably contained for reciprocating movement withinsaid second bore so as to be capable of pumping fluid into and out ofsaid one end of said primary conduit;

means for operating said first and second plunger, while said valvemeans is in said first position, so as to cause fi-uid to be pumped intosaid primary conduit and out of said discharge orifice;

means for thereafter switching said valve to said second positionthereof; and

means for thereafter operating said first and second plungers to pumpfluid out of said primary conduit whereby at least a portion of thefluid contained within that portion of said primary conduit between saidorifice and said common juncture may be withdrawn into said second boreand fluid may be caused to flow from said supply thereof, through saidsupply conduit, through said valve, through said other end of saidprimary conduit and into said first bore.

References Cited FOREIGN PATENTS 482,247 4/ 1952 Canada.

SAMUEL F. COLEMAN, Primary Examiner.

US. Cl. X.R.

